Powder actuated fastener driving tool



Sept. l0, 1963 L. w. BELL ETAL 3,103,013

POWDER ACTUATED FAsATENER DRIVING TooL Filed March 27, 1961 2Sheets-Sheet 1 INVENTORS LESTER E MULNO LEWIS WALTER BELL BY A TTORNEYS2 Sheets-Sheet 2 L. W. BELL ETAL POWDER ACTUATED FASTENER DRIVING TOOL94%/ their A TTORNEYS Sept. 10, 1963 Filed March 27, 1961 N @nl UnitedStates Patent O POWDER ACTUATED FASTENER DRIVING TOQL Lewis Walter Bell,Monroe, N. and Lester F. Mnlno,

Worcester, Mass., assign'ors to Star Expansion Industries Corporation,Mountainville, N.Y., a corporatlon of Delaware Filed Mar. 27, 1961, Ser.No. 98,635 14 Claims. (Cl. 1-44.5)

This invention relates to fastener driving tools, and more particularly,a new and improved tool for driving fasteners characterized by itssimple construction and safe operation.

Prior devices for driving fasteners such as studs, bolts, or the like byexplosion of a powder charge have been characterized by a complexity ofconstruction which Briefly stated, the tool of the invention comprisesthe combination of a breech `or tiring action assembly, a barrelassembly, and a handle arranged so that'the handle is coupled to thefiring action assembly by means of a single screw, removal of whichreleases the entire tiring action assembly from the remainder of thetool. The firing action assembly includes a breech housing wherein agenerally cylindrical breech block is spring-urged forwardly and inwhich a ring pin is slidably received. sear member mounted in the breechblock normally re'- strains the firing pin which is also spring-biasedin the forward direction with respect to the housing. A portion of thebreech block is formed with a recess for receiving a projection on atrigger member, the latter being mounted on a support block which isfastened to the outside of the breech housing. An inwardly projectingportion or the trigger support block is arranged to limit the forwardmotion of the breech block in the housing so that removal of the triggersupport block ing. 'In lthe uncocked position, the recess in the breechblock is in register with rt-he trigger projection, whereby actuation ofthe trigger is ineffective toirelease the firing pin land relativemotion of fthe breech block and the housing with` the trigger actuatedis impossible. Cocking i of the tool is accomplished by moving thebreech block rearwardly with respect to the housing and the trigger,whereby the trigger projection is brought into register with a part orfthe sear member. i

A safety shield surrounds the muzzle end of :the barrel of the tool tocatch fragments that may be dislodged from the work surface by operationof the tool, and this shield is rotatably mounted with respect to thebarrel of the tool to enable it to assume various positions with respectto adjacent objects on the work surface. In addipermits the breech blockto be'withdrawn #from the hous- FIG. 3 is a fragmentary sectional viewof the breech assembly of the tool taken along the lines 3-3 of iFlG. 1.i

Referring now to the drawings a typical tool` arranged according to thepresent invention comprises a handle 1, conveniently of the pistol gripcontigui-ation, a breech housing 2, and a barrel housing 3. As shown,the breech housing and barrel housing are of cylindrical shape, althoughany suitable configuration may be used. A safety shield 4 is provided atthe muzzle end of the tool.

Within the barrel housing 3 there is a barrel 5 hav-` ing a bore 5atherein for discharging a stud or other fastener While the breechhousing 2 encloses a breech block 6, which is of generally cylindricalconfiguration. A collar member 7 is rigidly fastened about the breech orrearward end of thebarrel 5 and this collar is arranged in the mannerdescribed below tobe rcleasably locked rto the breech block 6. In the-breech end of barrel 5 there is a breech plug 8 for receiving a powdercharge which may be a blank cartridge (not shown). 'Ille breech plug 8maybe slidably withdrawn from the breech end of the barrel S when thetool is in its opened or broken position with the barrel and breechblockdisconnected. f

The interlock arrangement between the breech `block 6` and the collarmember 7 may be of any suitable type, but preferably, it is of theinterrupted-.thread type known in the prior art. In this arrangement,segments of mating threads, indicated at 7a in FIG. 1, are formed in thebreech block 6 and the collar member 7 so that rotation of one withrespect to the other is required to bring the thread segments intointerlocking relationship."` In the present embodiment, the barrel andits collar are rotated while the breech block is held fixed, to terlock.

Also mounted within the breech housing 2 is a generally cylindricaltiring pin guide block 15 while, outside the breech housing, a triggersupport block 16 fastened to the housing 2 by means of two screws .17and d'8. rIhe screw 17 threadedly engages the firing pin guide block 15whereby both the guide block Iand the trigger support block are 'heldfixed with respect to the breech housing, the screw l18 being receivedin a threaded hole in a projection 18a on the breech housing 2. `Theprojection 18a lits closely in 1a corresponding `hole inthe triggerblock 16 and serves rto locate the trigger block and, consequently, thefiring pin guide block 15, accurately with respect to the breech housing2.

A trigger 9 is supported in a longitudinal slot inthe support block 16by a pivot pin 10 extending transversely through the block and it isformed with an inwardly extending projectiony 9a, adapted to extend intothe breech assembly as will be hereinafter described. A plunger andspring assembly 11 normally .urges the triggerv 9 toward a forwardposition lwith the projection 9a withdrawn from the housing and returnsthe trigger to this position after it is released. i

Slidably received in aligned bores in .the breech lblock 6 and tiringpin guide block- 15 is a firing pin 12. A compression spring 14supported on a guide pin 13 ex'- tending into an axial bore in thetiring pin .urges the pin `forwardly towards the barrel assembly but theforward motion of the firing pin is limited by :a ange 12b at the rearof the tiring pin which abuts the guide block 1S in the forward pinposition. Within the breech block 6 a sear lever 20 is pivotallysupported by a pivot pin 22 and is normally urged in a:counter-clockwise direction as viewed in the drawings by a Itorsionspring 2.1. In this condition, the inner end of the scar lever isaligned with a shoulder 12a on the tiring pin so that rearward motion ofthe breech block 6 and Ithe sear lever 20 will provide the in-V move thetiring pin rearwardly to a cocked position, comv pressing the tiring pinspring 14.

An opening 23 in the breech housing 2 adjacent to the trigger supportblock 16 permits the trigger projection l9a to communicate with thebreech block 6i.' When the breech block is in its normal, forwardposition with respect to the breech housing, a portion 24 of the breechblock, formed with a recess 24a, is located next to the opening 23 sothat operation of the trigger with the tool in this condition causes theprojection 9a to len-ter the recess 24a, inhibiting rearward motion ofthe breech block in the breechv housing. As a result, the tool cannot becocked while the itrigger is held in the actuated position. It" desired,the portion 24 may lcomprisea removable cover plate for lthe cavityinwhich the scar lever 2) is v'mounted. lTo the rear of the recess 24a,the breech block a forwardly-facing shoulder 25 which abuts a projection26 extending inwardly the trigger support block.16. This arrangementretains the breech block 6 in the breech housing 2 While the triggersupport block is in place, but permitsreasy removal of the breech blockwhen the support Iblock is removed.

Ailixed to the barrel housing 3 is a slotted block 27 havingr alongitudinal slot 27a Iformed therein. A transverse pin 28 is rigidlymounted in the forward end of the handle 1 and is arranged -to slidefreely within the 4slot 27a, the handle portion 1 being rigidly 4aflixedto the 'trigger support block 16 by means lof a single screw 28',

which is recessed in the grip portion of the handle. In addition,.thisScrew also retains a hanger member 29 having Ia hole near one end `topermit the tool to be hung onA a'hook or the like. From the foregoing,i-t will be seen that with the ,breech block interlocking arrangement in`the unlocked position, the handle poration and the breech housing maybe moved rearwardly of the barrel housing a distance equal to the lengthofslot 27a, which is made suflicient to enable complete separation ofthe breech block from the barrel. The handle may then be rotateddownwardly with respect to the Ybarrel portion, or tbrokenj vtofacilitate insertion lof projectiles and powder lcharges Iand removal ofspent cartridges.

, I-t will also be noted that the handle portion 1 is conto the triggersupport block 16 by means of a Asingle screw 28', removal of whichIcompletely frees the vhandle from trigger support block 16. The firingaction assembly may then be completely disassembled merely -by removalof the two screws `17 and 18 which anchor the support block to theassembly, since the projection 26 engaging the recess 2,5 on the breechblock 6 is the only means for retaining the breech block within thebreech housing 2.

'As shown in FIG. 3, which is a horizontal section through the breechassembly, a pairvof springs 30, mounted on spring guides 31 andextending the lfiring pin Y guide block 15 into recesses in the breechblock 6, urge the breech block forwardly within the :breech housing 2,the forward motion being limited as Idescribed above-by the projection26 and the shoulder 25.

It will Ibe readily apparent that the breech Iassembly can be completelydisassembled by rst removing the screw 28', which disconnects theibreech housing and the trigger support block Vfrom the handle 1, andthenrertiring pin 12, the spring 14 and spring guide 13 for the tiringpin. Upon reassembly, with )all of the components linv their prescribedplaces, it is necessary only to move the projection 26 into abuttingrelation with the forwardly- `facing Vshoulder 25 Ion the breech .block-to insure that the 4 hole in the housing 2 `for the screw 17 isproperly aligned with .the threaded hole in the guide block 1S.Accordingly, the breech assembly may be completely disassembled randreassembled with a minimum of manual dexterity and effort. It will alsobe noted that a mini- Vmuni num-ber of parts is used in the breechassembly which thus contributes to ease of manufacture and freedom frombreakdown problems.

The shield, indicated generally at 4, comprises a chamber deliningportion 4a and a sleeve portion 4b rigidly fastened thereto by weldingor the like. The .chamber dening portion 4a preferably is a metal shellof rectangular cross-section in the plane perpendicular to the barrelaxis, but if desired, the shield can have`other suitable shapes. In theassembled c-ondition, the sleeve 4b slidably engages the outer surfaceof the barrel 5 and is rotatable thereon to permitthe shield to beturned to any angular orientation with respect to the tool handle 1. Acartridge ejector pin 30a may be fastened, such as by riveting, to thechamber defining portion 4a of the shield to facilitate removal of spentcartridges from the breech plug 8.

The shield sleeve 4b ex-tends inwardly into the volume encompassed bythe chamber-defining portion 4a and terminates therein in an annular rim31 radially displaced from the barrel 5. A cap mit 32 threadedly engagesthe muzzle end of barrel 5 and includes an annular recess 32a forreceiving the rim 31 of the sleeve 4b. 'ln this way a labyrinth isformed between the shield chamber and the space between the barrel 5 andthe shield sleeve 4b, inhibiting the passage of dust and fragments fromthe shield into the tool. The nut 32 is provided with a central bore inregister with the bore 5a of the barrel. With the cap nut 32 in place,it can be seen that the shield 4 is free to rotate about the barrel 5 ort0 move towards the breech end of the tool. The shield cannot, however,be removed from the tool without rst removing the nut 32.

On the outer surface of the sleeve 4b there are a plurality of angularlydisposed longitudinal grooves 33 which cooperate with a spring biasedball detent 34 mounted in the projection on the barrel housing 3. Theshield structure 4 may then be rotated about the barrel axis andreleasably retained by the groove and detent -arrangement 33, 34, in'any one of a number of desired positions. The particular position ofthe shield structure desired may be Vdictated by the shape of thechamber defining portion 4a and the contour of the work against whichthe tool is used. There is thus provided a more versatile shieldassembly which reduces the operator hazard by adapting itself to varyingcontours of the work surface and adjacent objects.

'I'he shield 4 is normally maintained in its forward position asillustrated in FIG. 1 by a spring 35 surrounding the barrel `5 andretained under compression between the end 'of the sleeve 4b and awasher 36 which bears against an internal shoulder 3a formed in thebarrel housing 3. As will be obvious from this construction, the shieldassembly is urged toward the muzzle end of the tool so that the annularrim '31' normally bottoms in the recess 3211, and it can be movedrearwardly against the action of spring 35 independently of otherelements of the tool until the chamber `defining portion 4a meets thefront end of the barrel housing 3.

The shield assembly 4 is intended to safeguard the .operator and othersin the vicinity of the tool, and in order to prevent operationrwi-th theshield removed, a lock arrangement s provided. This lock arrangementcomprises a Z-shaped detent lever 38 mounted on a pin 39 fixed in theslotted block 27 which is mounted in the barrel housing 3. On one armthis lever includes a detent portion 38a and a chamfered portion 38b,the detent portion being adapted to engage an annular shoulder 5b formedon v'theexterior surface of the barrel 5. The chamfered portion 38b isnormally in contact with the conical surface of an annular ring 37mounted in the barrel housing 3. A

spring-biased plunger 40 urges the detent portion of the lever towardthe barrel adjacent to the shoulder 5b.

With the shield in place as required, the washer 36, under thecompressive force furnished by the spring 35, forces the ring 37 to theright, as viewed in FIG. 1 so that the conical surface engages thechamfered portion 3Sb of the lever 38, forcing the detent away from thebarrel 5 against the force of the spring and plunger 40. As long as theshield is in place, engagement of the detent 38a and the shoulder 5b isprevented `and the barrel 5 is free to move rearwardly in the housing topermit cooking of the tool. Upon removal of the shield, however, thecompressing force of spring 35 no longer is applied against the annularring 37 and the spring biased plunger 40 enables the lever 38 to pushthe ring out of the way and 'engage .the shoulder 5b. In this condition,the barrel 5 cannot be moved into cocking position, and therefore thetool cannot be tired by the operator. Upon reinsertion of the shield,the compressive force of spring 35 is reapplied andthe lever 33 isforced out of engagement with the barrel so that the tool can be cockedfor firing.

As illustrated in FIG. l, whenthe tool is in its uncocked or normalcondition, the breech block 6 and the barrel 5 are urged by the combinedaction of springs 30 and '35 to a forward position with respect to thehousing members 2 and 3 so that the forwardly-facing shoulder 25 of thebreech block abuts the projection 25 on the trigger support block 16.`In this position, the projection 9a on the trigger 9 is aligned withthe recess 24a and the trigger is unable to engage the sear lever 20.`It will also be noted that the shield 4 is in its most forward positionwith respect to the barrel housing 3i when the tool is in the uncockedcondition, the rim 31 being seated in the annular recess 32a of the capnu-t 32.

As illustrated in FIG. 2 which shows the tool inthe cocked condition,cocking is accomplished by pressing the muzzle end .of the tool againsta work surface 45 and displacing the barrel housing 3 and the breechhousing 2 forwardly with respect to the barrel and breech block againstthe force of springs 130 and 35 until the firing pin guide block abutsthe rear face of the breech block 6. During this motion the sear leverengages the shoulder 12a and prevents the tiring pin from rnovingforwardly with the guide biock 15, thereby compressing the tiring pinspring 14. At the same time the trigger projection 9a is moved intoalignment with the outer end of the sear lever 2t) so that actuation ofthe trigger 9 can pivot the lever 20 so as to release the tiring pin.When this is done the spring 14 drives the tiring pin forwardly into acorresponding opening provided in the breech block and into contact witha cartridge located in the breech plug to detonate the cartridge anddrive a projectile into the work surface.

It will be noted in FIG. 2 that a slight gap exists between the barrelhousing '3 and the chamber defining portion lda of the shield in thecocked position. This enables cocking to'be accomplished with the toolslightly displaced rfrom perpendicular to the work surface, and thusirregular surfaces may be more readily accommodated. If the tool istilted more than la yselected amount, however, for example five degrees,engagement of the forward end of the housing 3 with the shield 4 permitsthe barrel and the breech block tot move forwardly within the housing asufficient distmce so that the trigger projection 9a no longer isaligned with the scar lever 20 and the tool cannot be tired. Removal ofthe muzzle end of the tool from the work surface permits the springs andy to restore the breech block, barrel and shield to their forwardpositions with respect to the housings 2 l and A3. As this is done thefiring pin 12 is` Withdrawn from the breech block 6 by the guide block:15 and the sear lever 20 returns to its normal position under theintluence of the spring 21.

As discussed hereinabove, the breech locking arrangement preferably usedwith the present invention is of the (i interrupted thread type,requiring relative rotation between the barrel collar 7 and breech block6 to lock` the two parts together. To enable this locking action to beperformed simply, as well as to provide a further safety feature whichprevents tiring of the tool with the breech in the unlocked condition, apin and slot arrangement is provided. This arrangement comprises anangular slot 41 `formed in the barrel housing 3` adjacent to the breechhousing 2 fand a longitudinal slot 42 in the breech housing extendingfrom one end of the slot 41, the slots 411 and 4-2 forming an L-shapedcutout in the tool housing when the tool is in its closed condition.Rigidly aflixed to barrel collar 7 and extending radially therefrom is apin 43, adapted to be received within the slots yil and 42. A frictionplate d4 aiiixed to the outer end of the pin 43 facilitates actuationthereof by the operator.

In the uncooked condition of the tool, the pin 43 is located in the slot`d1 and angiilar motion of the pin there` in serves Ito lock or unlockthe barrel and breech block. ln the unlocked position, the pin 43 islocated in the upper portion of the siot 41 as viewed in FIG. 2, andthus it prevents the barrel and the breech block from being movedrearwardly with respect to the housing so that the tool cannot becocked. With the pin 43 "at the other end off the slot 41, theinterrupted thread arrangement is in the locked condition and, since theslot 4Z extends longitudinally from that end of the slot 41, the housingcan now be displaced Iforwardly with .respect to the barrel and breechblock to allow the tool to be cocked. When the pin d3 is in itsuppermost position in. the slot 41 as viewed in FIG. 2, the breechlocking mechanism is unlocked and the handle portion of the tool may beWithdrawn from the barrel portion and pivoted about the pin 2S to exposethe breech plug 8. 'Il-'nis slot and pin arrangement therefore providesa simple device exterior of the tool for opening the tool lfor loading,as well as providing a safety lock for preventing firing of the toolwith the breech in the unlocked condition. Moreover, the pin 43 providesa forward stop for the barrel 5 in its housing 3 by its engagement withthe edge of the slot 41.

It is apparent from the preceding disclosure that the barrel and shieldcan easily be withdrawn from the housing by merely removing the cap nut32 from the barrel muzzle. When the cap nut 312 is removed from themuzzle of the barrel 5, the shield 4 can of course immediately bewithdrawn forwardly from the barrel housing 3. However, inasmuch as thebarrel 5 is attached to Ithe collar member 7, whose cross-sectionaldimensions are greater than the minimum interior cross-sectionaldimensions of the barrel housing 3 forwardly of the collar '7, thebarrel 5 can be withdrawn `from the housing 3 only rearwardly. Moreover,the barrel 5 cannot be withdrawn from the barrel housing 3 unless thetool is first broken and the detent portion 38a of the Z-shaped detentlever 3S made to alhord passage for the annular shoulder 5b on thebarrel 5. There :are two ways of making the portion 38a afford suchpassage after the cap nut 32 is removed. First, a small sharp tool suchas a nail may be engaged with the end of the lever 38 opposite theportion Stia and employed to= force the lever 38 counterclockwise asseen in FIG. l. (The end of the lever 38 opposite the portion Et/z is ofcourse accessible from the rear when the tool is broken.) Alternatively,the annuiar ring 37 may be held against the chamfered portion 38h lofthe lever 3S even after the cap nut 32 is removed. A convenient way toretain the annular ring 37 in the desired position after the cap nut 32is removed is to hold the shield 4 inV position manually [after the capnut 32 is removed so that the spring 35 continues to bear against thewasher 36.

In operation, an appropriate fastener yof a conventional type isinserted in the breech end of the bore 5a, the tool being Iopened in themanner previously described. A suit able blank cartridge is theninserted in the breech plug and the tool is closed by pivoting thebreech portion into 7 t alignment with the barrel portion and moving itforwardly to engage the locking mechanism. Operation of the k pin 43 tothe lower position in the slot 41, as` viewed in the drawings, iocks thetwo parts of the tool together. As previously mentioned, the tool is redby pressing the muzzle end of the barrel against the workpiece, movingthe housing forwardly with respect to the barrel and breech -b-lock, andactuating the trigger. After release of the firing pin, as discussedabove, and detonation of the cartridge, the tool is then broken again,and the breech plug is removed and slipped over the pin Stia to removethe spent cartridge. The tool is then ready for reloading andapplication of another stud to the work surface.

As is apparent from the foregoing, the structure of the presentinvention provides a fastener driving tool which is extremely simple inconstruction, providing ease of maintenance and'repair. The improvedsafety features render improper tiring of the tool virtually impossible;the tool being incapabie of being fired in the uncooked position, withthe breech unlocked, with the shield removed, .or when tiltedappreoiably with respect y to the Work surface.-

While a representative embodiment of the present invention has beenshown and described for purposes of illustration, various changes andmodifications may be made therein by those skilled in the art withoutdeparting from the principles of this invention. Therefore, all suchchanges and modifications are included within the intended scope of theinvention as defined by the folrlowing claims.

We claim:

1. A powder actuated fastener driving tool comprising housing means,barrel means slidably mounted in the housing means having a breech endadapted to receive a fastener and a powder change and a muzzle endadapted to be placed against a work surface in which the fastener is rtobe driven, rbreech block means slidably mounted in the housing means andengageable with the breech end of the barrel means, spring means urgingthe breech block means forwardly within the housing means, and abutmentmeans mounted externally of the housing means and having a projectionextending into the interior of the housing means operatively associatedwith the breech block means to limit the forward motion thereof, theabutment means being removable from the housing means to permit thefbreech block means to be withdrawn from the housing means.

2. A powder actuated fastener driving tool according to claim 1 whereinthe abutment means comprises a trigger support block and includingtrigger means pivotally mounted lon the support block having aprojecting part movable into operative association with the breech blockmeans.

3. A powder actuated fastener driving tool according to claim 2including further abutment means mounted within the housing meanslimiting rearward motion of the breech block means therein, andV scarmeans movable with the breech block means between la rearward positionin which it is aligned with the projecting part of the nigger means topermit operation of the scar means by the trigger means and a forwardposition in which the sear means is out of line with the projecting partof the trigger means.

4. A powder actuated fastener driving tool comprising housing means,barrel means mounted in the housing means having a breech end adapted toreceive a fastener and a powder charge and a muzzle end adapted to beplaced against a workpiece in which fthe fastener is to be driven,breech block means mounted within the housing means engageable thebreech end of the barrel means, firing pin means slida'bly receivable inthe breech block means, spring means urging the tiring pin meansforwardly in the breech block means toward the breech end of the barrelmeans, cocking means movable within the housing means between a normalforward position land a rearward position and adapted to drive the yfiring pin means rearwardly to a cocked position in response to rearwardmotion, trigger means mounted externaily of the housing means having aprojecting part movable into the housing means upon actuation of thetrigger means, and element movable with the cooking means and formedwith a recess positioned to receive the projecting part of the triggermeans when the trigger means is actuated with the cooking means in itsforward position, thereby preventing rearward motion of the cockingmeans. 1

5. A powder actuated fastener driving tool comprising housing means,barrel means mounted in the housing means having a breech end and amuzzle end'and normally movable between a forward position and arearward position with respect to the housing means, rearward motion ofthe barrel means in the housing means being effective to cock the tool,deflector shield means surrounding the barrel means near the muzzle endfor engagement with a surface into which a fastener is to be driven,sleeve means surrounding the barrel means and supporting the shieldmeans for relative longitudinal motion with respect to the barrel means,abutment means within the housing means, washer means surrounding thebarrel means and normally abutting the abutment means, spring meansextending between the washer means and the shield means urging theshield means forwardly with respect to the housing means and the washermeans rearwardly against the abutment means, collar means surroundingthe barrel means engaging a rear surface of the washer means and havinga rearwardly facing cam surface, the outer surface of the barrel meansbeing formed with a recess, and detent means mounted in the housingmeans and radially movable with respect to the barrel means having a rstportion adapted to project into the recess in the barrel means toprevent rearward motion thereof with respect to the housing means and asecond portion engaging the cam surface of the collar means so that the'first portion is normally held away from the recess in the barrelmeans, whereby removal of the force applied by the spring means permitsthe collar means and the washer means to move forwardly on the barrelmeans so that the second detent portion is released from the cam surfaceand the first detent portion is permitted to move into the recess in thebarrel means.

6. A powder actuated fastener driving tool according to claim l5 whereinthe detent means comprises a lever member pivotally mounted in thehousing means having one end formed with said rst and second portionsand spring-biased toward the barrel means.

7. A powder actuated fastener driving ltool comprising housing means,barrel means mounted in the housing means having a muzzle end projectingtherefrom, deflector shield means surrounding the muzzle end and adaptedto engage a surface into which a fastener is to be driven, an annularlip projecting forwardly from the shield means and surrounding thebarrel means, and cap means mounted on the muzzle end of the barrelmeans having an annular groove normally receiving the annular lip of theshield means, thereby forming a labyrinth between -the shield and theouter surface of the tool barrel to inhibit the passage of particlesfrom the shield 4into the tool.

8. A powder actuated fastener driving tool according to claim 7 whereinthe shield means is longitudinally movable with respect to the barrelmeans and engagement of the annular lip with the cap means provides aforward stop for the shield means and including spring means for urgingthe shield means forwardly with respect to the barrel means.

9. A powder actuated fastener driving tool comprising housing means,barrel means mounted in the housing means having a muzzle end projectingtherefrom, deflector shield means surrounding the muzzle end and adapted9 to engage a surface into which a fastener is to be driven, sleevemeans aixed to the shield means and surrounding the barrel meanssupporting the shield means for angular motion with respect thereto andto the housing means, means forming a plurality of angularly disposedrecesses in the outer surface of the sleeve means, and detent means axedto the housing and engageable selectively in any of the recess means toreleasably retain the shield means in any of a plurality of selectedangular positions with respect to the housing means.

A10. A powder actuated fastener driving tool according to claim 9wherein the sleeve means supports the shield means for longitudinalmotion Iwith respect to the housing means and the recesses compriselongitudinal grooves in the outer surface of the sleeve means.

1-1. A powder actuated fastener driving tool comprising housing meansincluding a generally tubular rear housing member and a generallytubular front housing member adapted to be held in aligned and abuttingrelation, barrel means supported for limited rotative and longitudinalmovement in the front housing member, breech block means supported inthe rear housing member for limited longitudinal movement and in iixedangular relation with respect thereto, connecting means associated withthe breech block means and the barrel means requiring relative rotationthereof, the end of the front housing member adjacent to the rearhousing member having an angular slot formed therein and the rearhousing member having a longitudinal slot formed therein extending fromone end of the angular slot in the front housing member, and radial pinmeans aixed to the barrel means and movable in the angular slot betweena first block means forwardly in the rear housing member, and abutmentmeans mounted externally of 'the housing means having a projectionextending into the interior of the rear housing member operativelyassoci-ated with. the breech block means to limit the forward motionthereof, the abutment means being removable Vfrom the housing means topermit the breech block means to be withdrawn from the rear housingmem-ber.

13. A powder actuated fastener driving tool according to claim l2wherein the breech block means is longitudinally movable between aforward position and a rear position with respect to the housing meansand has a longitudinal passage and including tiring pin means receivablein the longitudinal passage, spring means urging the firing pin meansforwardly with respect to the housing means, -sear means mounted on thebreech block means position aligned with the longitudinal slot whereinthe Y having ya first portion normally Valigned with the ring pin meansand a second portion, and ltrigger means pivotally supported on fthehousing means having 4a projecting part movable into the housing meanswhen the trigger means is actuated, the projecting part of the triggermeans being aligned with the second portion of the sear means when thebreech block means is in its rear position with respect to the housingmeans, the breech block means bein'g formed with a recess positioned toreceive the projecting part of the trigger means when the breech blockmeans is in its forward position in the housing means, therebypreventing rearward motion of the breech block means when the triggermeans is actuated.

14. A powder actuated tool according to claim 13 including connectingmeans between the two housing portions comprisinga handle memberpivotally joined to the front housing member and removably connected tothe abutment means on the rear housing portion.

References Cited in the le of this patent FOREIGN PATENTS

1. A POWDER ACTUATED FASTENER DRIVING TOOL COMPRISING HOUSING MEANS,BARREL MEANS SLIDABLY MOUNTED IN THE HOUSING MEANS HAVING A BREECH ENDADAPTED TO RECEIVE A FASTENER AND A POWDER CHARGE AND A MUZZLE ENDADAPTED TO BE PLACED AGAINST A WORK SURFACE IN WHICH THE FASTENER IS TOBE DRIVEN, BREECH BLOCK MEANS SLIDABLY MOUNTED IN THE HOUSING MEANS ANDENGAGEABLE WITH THE BREECH END OF THE BARREL MEANS, SPRING MENAS URGINGTHE BREECH BLOCK MEANS FORWARDLY WITHIN THE HOUSING MEANS, AND ABUTMENTMEANS MOUNTED EXTERNALLY OF THE HOUSING MEANS AND HAVING A PROJECTIONEXTENDING INTO THE INTERIOR OF THE HOUSING MEANS OPERATIVELY ASSOCIATEDWITH THE BREECH BLOCK MEANS TO LIMIT THE FORWARD MOTION THEREOF, THEABUTMENT MEANS BEING REMOVABLE FROM THE HOUSING MEANS TO PERMIT THEBREECH BLOCK MEANS TO BE WITHDRAWN FROM THE HOUSING MEANS.